Why Does the Middle Bulb Glow Brighter in a Parallel Circuit?

In a parallel circuit, each component is connected directly to the power source, allowing each bulb to receive the full voltage. If one bulb (the middle one, in your case) has a lower resistance than the others, it will allow more current to flow through it compared to the other bulbs.

This increased current results in a brighter glow for the middle bulb because brightness in incandescent bulbs is directly related to the power (P = I²R) dissipated in them. Since the middle bulb has lower resistance, it experiences a higher current, leading to greater power and, therefore, a brighter light.

In your parallel circuit with bulbs rated at 5W, 25W, and 5W, the middle bulb (25W) glows brighter because it is designed to handle more power than the others.

When connected to 230V, each bulb receives the full voltage. The 25W bulb draws more current than the 5W bulbs due to its lower resistance (P = V²/R). This increased current results in greater power dissipation, making the 25W bulb shine brighter compared to the 5W bulbs, which draw less current and produce less light.